The Navistar VT365 (aka: Ford 6.0L diesel) was actually a fine engine. There are still plenty of them still around in School Buses, Ambulances, Wreckers, etc.
But Ford wanted more power in order to compete with generic motors (Isuzu, actually) and Dodge's Cummins. Both of which had more than their fair share of problems during that time. Believe it.
So Navistar boosted the VT365 beyond its abilities and bad things happened. If you can get a 6.0L Ford on the Cheap and bulletproof it, you've got a good engine. The 6.4L, OTOH, you wanna run from them.
I can see emissions requirements on Highway diesel engines. I would even encourage it to a degree. (Some better engineering would be of great benefit)
But it's the wrong people doing it. The EPA is a collection of eco-terrorists and old hippies thrown in with modern day anarchists that hate everything about us. fact
Which is why we have to put up with it on Tractors. Tractors aren't hurting anything. They're way out in the boonies. Any carbon (soot, etc) they might emit settles to the ground long before it reaches population centers.
And in case some adherrents to the EPA cult (which is what it is anymore. No science, cult) missed it, ALL life on Earth is based on carbon.
shock